(1) Field of the Invention
This invention relates to soaps of C.sub.22 -cycloaliphatic tricarboxylic fatty acids. This invention also relates to a method for making the C.sub.22 -cycloaliphatic tricarboxylic fatty acid and the soaps as well as their use as hydrotroping agents for normally insoluble nonionic synthetic detergents in alkaline mediums. More particularly, this invention relates to C.sub.22 -cycloaliphatic tricarboxylic acids formed by the reaction of conjugated linoleic acid and fumaric acid via a Diels-Alder addition and soaps made therefrom.
(2) The Prior Art
Reactions of linoleic acid and linoleic acid containing natural fatty acid mixtures with fumaric acid are well known. In instances where no iodine is present and the temperature is above about 240.degree. C., this reaction is known as the "ene" reaction where the addition occurs at a double bond site in the fatty acid chain forming a branched tricarboxylic acid. The "ene" reaction does not form a cycloaliphatic tricarboxylic acid; and in the usual case, the reaction temperatures are higher than Diels-Alder reactions and the "ene" reaction does not proceed cleanly in the presence of iodine. Examples of "ene" adducts are shown in German Patent No. 973,398 to Stein et al. Another example in U.S. Pat. No. 3,890,259 to Montesissa et al.
As stated, the subject invention includes making tricarboxylic acids that are Diels-Alder adducts. C.sub.21 -tribasic acids made from conjugated linoleic acid and dienophiles, such as maleic acid or maleic anhydride and the like, are disclosed in British Patent No. 1,032,363 and U.S. Pat. No. 3,412,056 both to Crawford et al., wherein conjugated fatty acids are isomerized to a trans/trans form and subsequently reacted with a reactive dienophile to form the Diels-Alder adduct. The Diels-Alder reaction was applied to fatty acids containing both conjugated linoleic acid and non-conjugated linoleic acid wherein the non-conjugated portion of the linoleic acid was also converted to a C.sub.21 -dicarboxylic acid using acrylic acid as the dienophile in Ward, U.S. Pat. No. 3,753,968 and soaps therefrom were taught in Ward, U.S. Pat. No. 3,734,859.
It is, therefore, a general object of this invention to provide new C.sub.22 -cycloaliphatic tricarboxylic acid soaps.
Another object of this invention is to provide a process for making C.sub.22 -cycloaliphatic tricarboxylic acids from all of the available linoleic acid in a fatty acid mixture.
Still another object of this invention is to provide a process whereby tall oil fatty acids and soya bean fatty acids may be converted into a C.sub.22 -cycloaliphatic tricarboxylic acid and an oleic acid portion and thereafter easily separated.
Yet another object of this invention is to provide a C.sub.22 -cycloaliphatic tricarboxylic acid as a hydrotroping agent for nonionic synthetic detergents.
Other objects, features and advantages will be evident from the following detailed description of the invention.